Valley Fever (Coccidioidomycosis)


US Map - Estimated areas with coccidioidomycosis (Valley Fever) in the United States

Estimated areas with coccidioidomycosis (Valley fever) in the United States

Valley Fever, or Coccidioidomycosis (pronounced [käkˌsidēˌoidōmīˈkōsəs]), is an illness caused by the soil fungus Coccidioides that lives and grows in dry regions of the Western United States. There were approximately 20,000 infections diagnosed in the US in 2019, with the greatest number of cases diagnosed in California and Arizona.

Spores of the fungus are spread through the air when soil is disturbed (e.g., cultivating, excavating, high winds). People who inhale spores may develop a lung infection with symptoms including cough, fever, shortness of breath, headache, fatigue, body aches, night sweats, and rash. Valley Fever cannot be transmitted from person to person.

Additional information about Valley Fever is available from the Centers for Disease Control and Prevention.

Valley Fever and Workers

Exposure is most common among outdoor workers whose jobs require digging, trenching, excavation and movement or removal of soil, but all workers exposed to outdoor dust in the Western United States can get Valley Fever. Jobs with increased risk of Valley Fever infection include:

Climate and Expansion

Coccidioides growth is dependent on air temperature, precipitation, plant cover, soil moisture, and surface dust concentration. Valley Fever can be contracted any time of the year but is more likely after long, dry periods. Droughts caused by climate change may expand western drylands, creating a larger habitat for Coccidioides. Although most cases of Valley Fever have been reported in western states, workers exposed to dusty outdoor environments should be aware of the signs and symptoms of Valley Fever and the potential for infections to occur in new regions.

Excavator: iStock-1174057859
  • Agricultural workers
  • Landscapers and gardeners
  • Ranchers
  • Construction workers, miners, and oil field workers who use heavy digging equipment or are trenching
  • Renewable energy workers
  • Workers in the entertainment industry
  • Archeologists
  • Geologists
  • Wildland firefighters
Quick Facts about Valley Fever